I tried to install Ubuntu 12.04 LTS in the second HDD by using Unallocated space.
I tried for 6 times. Each time it got installed, but after first restart, it directly boots Windows XP in the first HDD and no boot options appear. Every time I found that the Ubuntu installation used unallocated space and made two partitions one EXT3 and other Linux swap.

I don't know what went wrong. During Installation, Ubuntu detected Windows XP. Can anybody help me?

I will try the same after installing Ubunto 12.04 again, because I deleted the earlier installation. However, I found that Ubuntu is changing the MBR code in first Hard disk every time. I assume that the modification done by ubuntu is to pint to the location of GRUB ?
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chachuAug 9 '12 at 17:07

Thank you Wegko, your suggestion worked.Also I am able to boot the other drive from GRUB, ie it lists Windoxs XP in the first drive as option. Now my Swap partition is only 500MB how can I increase it to 2 GB?
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chachuAug 10 '12 at 12:29

That should be a separate question, but I've seen it asked before so it's fine. Use gparted, basically. gparted.sourceforge.net Ubuntu has it installed by default or available through repositories.
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WegkoAug 10 '12 at 15:21

this may be because you can't see the options due to default grub screen resolution problem!! For this when boots and shows black screen just press up arrow five to six times and then press enter. You may able to boot ubuntu... then to change the graphical boot property just install grub customizer and customize your grub...